The purpose of this application for grant support is to allow a collaborative study on the topography of glycosylation reactions in the rough endoplasmic reticulum between Dr. Carlos Hirschberg's laboratory (University of Massachusetts Medical Center, Worcester, MA) and Dr. Armando Parodi's laboratory (Fundacion Compomar, Buenos Aires, Argentina). The long term goals of this proposal are to understand how precursors in protein and lipid glycosylation can be translocated across the membrane of the endoplasmic reticulum, from the cytosolic side to the lumenal side. This translocation is believed to play an important regulatory role in protein and lipid glycosylation. The Specific Aims of this proposal are to determine whether dolichol-P- glucose is synthesized on the cytosolic side of the endoplasmic reticulum membrane and if so, by what mechanism this lipid-saccharide is subsequently translocated across the membrane into the lumen where it serves as a substrate for further glycosylation reactions. These studies will complement ongoing research in Dr. Hirschberg's laboratory dealing with the cell biology, biochemistry & molecular biology of glycosylation reactions, with Dr. Parodi's laboratory on the chemistry and biochemistry of dolichol oligosaccharides.